Known high voltage transformers, for example, in the voltage range from 1 kV to 72.5 kV or higher can be embodied as dry transformers that include an output capacity in the range of 0.5 MVA to 63 MVA, for example. However, for some applications, transformers of this type should be arranged in a protective housing. This can be for various reasons, by way of example that the transformer is to be protected from harsh environmental conditions such as saline sea air. In such a case, the protective housing can be a hermetically encapsulated housing, wherein the thermal energy that arises in the housing during normal operation is dissipated to the outside by a heat exchanger. However, transformers are also accommodated in a protective housing as specified in order to protect personnel and to prevent any human contact with any parts that are carrying voltage. Transformers that have a higher output capacity by way of example 200 MVA and higher are embodied as oil transformers. In this case, the transformer is arranged in an oil-filled vessel that ultimately also represents a protective housing in terms of the disclosure.
It is however disadvantageous that arc faults can occur in the event of a fault between voltage-carrying parts of the transformer or its supply lines through the protective housing and the housing that is grounded for safety reasons. An arc fault of this type includes a high energy density and can in the event of a short circuit completely destroy a normal protective housing depending upon the respective feed-in of power from the supply network. For this reason, protective housings are available for transformers that are designed in such a manner that an arc can burn in the internal compartment of the transformer for a specific period of time without posing any risk to personnel or damaging the protective housing. A representative example is disclosed in WO 2012118645 A1. Protective housings of this type are however extremely costly to produce. The term ‘protective housing’ is understood in each case also to mean an encapsulation.